The election notices arrived in hundreds of Pittsburgh-area workplaces, setting off internal campaigns lasting weeks and involving thousands of employees. Each election ended with workers dropping by breakrooms and offices to cast their ballots.

Individually, the vote tallies were often relatively small, quietly held affairs. But taken as a whole, they represent the future of labor unions in a region with deep organizing roots, ahead of a U.S. Supreme Court ruling expected this month that could significantly shake up union membership.

About four dozen unions — led by the Service Employees International Union, the United Steelworkers and the International Brotherhood of Teamsters — have petitioned for nearly 300 elections since 2010, according to a Post-Gazette analysis of votes certified by the National Labor Relations Board. In those elections, unions have added more than 8,000 workers in the Pittsburgh region to membership rolls.

A Supreme Court ruling in the Janus vs. AFSCME case is widely expected to allow public sector workers to stop paying membership dues, which would severely crimp unions’ resources if enough members opt out.

Against that backdrop, the efforts to win employee votes take on new significance as labor organizers work differently than they did in the 1930s, even the 1990s. Now it’s all about reaching smaller groups of employees, often in workplaces where unions traditionally didn’t play a role.

“The world sees union membership as antiquated, and that’s the wrong assumption to make,” said Maria Somma, director of organizing for the United Steelworkers, which gets 25 to 30 calls a day from workers across North America who want to join the Downtown-based union.

Labor organizations in this region have already adapted to shifts in the market, Ms. Somma said, as the large industrial facilities that were big prizes during organized labor’s heyday have been replaced by hospitals, schools and casinos.

“They have replaced the US Steels and ATIs,” she said. “When we look at growth and targets for our union, we have to look at where we can make the most impact, where workers actually need us.”

At the same time, the wins and losses — for the most part not trumpeted by unions or companies — show that union elections since 2010 have often been remarkably close decisions.

Unions had the slight edge in ballots cast — 51 percent — and won about 55 percent of regional elections — 161 of 292 — posted by the labor board.

Smaller workplaces, unfamiliar industries

As workplaces have fractured into smaller units, different unions have jostled for members — often in the same building.

Unions run into each other at the same workplace all the time, Ms. Somma said, but the relationship is usually respectful. “We pick up the phone, and we try to sort out issues with each other, and it’s worked really well. We try not to interfere because 90 percent of the workforce is unorganized, and it seems silly to fight over it.”

Take a typical casino, for example.

The International Brotherhood of Teamsters wants valet parking attendants. The International Union of Operating Engineers wants the slot machine technicians and the building maintenance workers. The International Union, Security, Police and Fire Professionals of America wants the security guards. The Service Employees International Union wants the janitors. Unite Here wants the hospitality staff.

And the United Steelworkers wants card dealers.

The USW, which counts 850,000 members across North America, has begun an organizing campaign for about 270 dealers at the Meadows Race Track and Casino in North Strabane. That campaign is nearing an end, with an election petition expected in the coming weeks, said Phil Gitzen, a card dealer at the Washington County casino for about four years.

Before the campaign began, a few of the dealers reached out to the USW amid concerns that recent changes in ownership would result in unfair and arbitrary cuts, Mr. Gitzen said.

“Some people are concerned about pay and benefits, but I’m more concerned about having a say in what goes on,” he said. “Unless you have something in writing, the promises of today can change tomorrow.”

Big prizes

Education and health care organizations are generally still large institutions, and the Service Employees International Union, with divisions to bargain for health care workers and building janitors, has been a central player.

The SEIU has by far the best numbers of any union in the region, notching wins in 21 of 26 elections since 2010 with 67 percent of ballots cast in favor of union representation.

In 2015, the SEIU organized about 1,400 service, technical and office employees in three elections held at Allegheny General Hospital on the North Side. The SEIU has also organized small units with 7, 9, 11 employees — each at health facilities.

“[While] health care giants continue to grow and expand, I think workers continue to see their ability to shape front-line care and experience good jobs and have their own interest advance slips away,” said Matt Yarnell, president of SEIU Healthcare Pennsylvania.

The USW’s biggest wins in the region came in education — organizing hundreds of professors at Robert Morris University, Point Park University and Duquesne University.

Warning signs

But with the Janus case looming, the work doesn’t stop when a union is elected. Close votes could be warning signs ahead for labor organizations trying to maintain their clout at the bargaining table.

Even in union workplaces, members unhappy with representation can hold a decertification vote — with 30 percent of membership signing a petition — to oust a union.

Last year, nearly 200 workers voted to decertify the USW at UniFirst Corp., a manufacturer and distributor of uniforms, in New Kensington. In January, the SEIU survived a decertification vote at UPMC McKeesport, which last week reached a new contract deal.

Going forward, the winning formula will rely on simple, old-school tests of solidarity, said Keith Thurner, business manager for the International Union of Operating Engineers Local 95.

The small Greenfield-based union, without a permanent organizer on staff, has won the majority of elections and 56 percent of the vote in 17 elections.

Mr. Thurner tells potential members, “You guys have to want it, but we also want to have you,” he said. “We’ll invest time and money, we’ll run the gamut for you, but we need to make sure you guys are all in.”